The invention relates to attachable couplings for hose, but more particularly, the invention relates to a deformable ferrule for use in coupling hose.
Couplings that are post assembled to flexible hose typically have a male stem portion that is insertable into a hose end and a ferrule that is concentric with the male stem. The ferrule may be preattached to the male stem or post attached to the male stem during a coupling process requiring deformation of the ferrule. Together, the male stem and ferrule define an annular cavity for receiving a hose end. The coupling is retained to the hose end by pinching or compressing it between the ferrule and stem. The ferrule may be preattached to the stem such as by crimping an end portion of the ferrule to a stem collar so that the annular hose receiving cavity is formed. A ferrule as a separate part, may be attached to a collar of the stem when the ferrule is deformed such as by crimping or swaging.
Some ferrules have a smooth bore and are deformed during crimping to provide what is known as a "ripple crimp" where a plurality of annular ridges and grooves are formed in the ferrule sidewall. The male stem may have a plurality of annular serrations or grooves to aid in gripping a hose end when a ferrule is deformed during the coupling process.
In some applications, circumferential, helical, or longitudinal ribs are provided on the inside of the ferrule to aid in gripping a hose end. Such ribs may contact an embedded reinforcement of the hose for greater coupling retention. The ferrules may be deformed to a generally cylindrical exterior shape such as by crimping or swaging.
A preattached ferrule having a constant wall thickness and a frustoconical shape to aid in inserting a hose end prior to deformation is shown in U.S. Pat. No. 3,530,900. During the coupling process, the frustro-conical shaped ferrule is crimped to have a generally cylindrical shape with a plurality of circumferential ribs and grooves that cooperate to pinch the hose end.
A post attached ferrule is exemplified by U.S. Pat. No. 4,305,608. The ferrule has a plurality of longitudinally oriented ribs that are capable of penetrating a hose cover to embed with a hose reinforcement when the ferrule is deformed to have a generally cylindrical exterior shape. During crimping, portions of the ribs are deformed against a stem collar to define a means for attaching the ferrule to the male stem.
Another example of a preattached ferrule is shown in U.S. Pat. No. 4,226,446. A serrated stem and ferrule with a "ripple crimp" is used to pinch a hose end and retain a coupling. A difference in the pitch spacing between a "ripple crimp" and serrations on a male stem causes the hose to be pinched in progressively reduced amounts of compression even though the ferrule and stem define a generally annular cavity for receiving the hose end. While reduced pressure zones are recognized as being beneficial to minimize local stresses in a coupled hose end for improving coupling retention, special care must be taken to ensure that the pitch spacing of the ripple crimp is properly located with respect to the pitch spacing of the male stem so that reduced pressure zones are achieved.
Although U.S. Pat. No. 3,530,900 shows generally a pre-crimped frustoconical cavity for receiving a hose end, it and U.S. Pat. Nos. 4,226,446 and 4,305,608 show post crimped annular cavities for pinching or compressing a hose end. Of these, only U.S. Pat. No. 4,305,608 appears suitable for high pressure hose applications as indicated by ferrule ribs directly contacting a hose reinforcement.